Dean M. Chriss
(Click image to enlarge)
Methuselah sprouted in 2832 BCE, before the Egyptian pyramids were
built, and just as the stone age was ending. It was already 4324 years old when
Christopher Columbus purportedly discovered America, 4,608 years old when
America's Declaration of Independence was signed, and became 4852 years old in the year 2020.
Methuselah is the oldest known living individual of any species on Earth.
This bristlecone pine specie, Pinus longaeva, is among the longest living
life forms in the world. They have the unique ability to survive harsh
conditions by allowing parts of themselves to die so other parts can
survive. The older a tree gets, and the more adversity it endures, the more
of it is dead wood. The oldest trees might have only a few small living
branches with green needles and a small strip of bark on one side bringing
moisture and nutrients to it. As you can see here, Methuselah is still
producing pine cones.
When these trees die they often remain standing on their roots for
many centuries and the fallen dead wood lasts for thousands of years longer. Because these bristlecone pines do not compete well with other plants
and trees, they are typically found in conditions that are too harsh for
most other plants to survive. High altitudes, poor soils, and little
moisture make the ideal environment for these trees. It is interesting that
the same trees living in what would normally be considered "better"
conditions grow faster but do not have an exceptionally long lifetime.
The warming climate also makes these trees grow faster, and that makes them more
susceptible to insects and disease. Specifically, white pine blister
rust is a lethal, nonnative disease of white pines that can infect the
ancient bristlecone pines. It was introduced to North America via
Europe from Asia in the early 20th century and was first discovered in Colorado in
1998. Since then it has slowly continued to spread across the continent. This 20th century
human introduced pathogen will probably end the story of these ancient trees in what,
relative to their age, is the blink of an eye.
All living things absorb radioactive carbon from the atmosphere while they are alive and stop
doing so after death. At that point the absorbed radioactive carbon decays
at an exact rate. That allows us to determine how long ago the living
material (wood, bones, plants, etc.) died based on how much radioactive
carbon remains in the sample. For that process to be accurate the
concentration of radioactive carbon in the atmosphere must be accurately known. We used to
think the concentration was constant over large time spans, but these trees taught us that
it was not. Bristlecone pines give us a tree ring history going back nearly
10,000 years. By radioactive carbon dating the ring samples, which have
exactly known ages, it was found that the amount of
radioactive carbon in the atmosphere varied considerably over time. That in
turn allowed calibration of the radioactive carbon dating process, making it
much more accurate and changing our understanding of where and when human